China's lake expansion amplified rapid CO₂ emissions

Area of Science:

• Environmental Science
• Climate Science
• Geoscience

Background:

• Carbon dioxide (CO2) emissions from lakes are significant to the global carbon cycle.
• Long-term dynamics of lake CO2 emissions are not well understood.
• China's lakes are expanding, potentially impacting their role in carbon cycling.

Purpose of the Study:

• To quantify nationwide changes in lake CO2 emissions across China.
• To investigate the relationship between lake expansion and CO2 emissions.
• To assess the contribution of lake CO2 emissions to the national carbon budget.

Main Methods:

• Utilized a compiled lake CO2 flux dataset.
• Employed a machine learning model for analysis.
• Incorporated lake area data to track expansion.

Main Results:

• Nationwide lake CO2 emissions in China increased from 11.25 to 13.94 Tg C/year between 2000 and 2021.
• A significant increase in emissions occurred after 2010, coinciding with rapid lake expansion (71–462 km²/year).
• Large lakes (>50 km²) contributed ~62% to total emissions, and lake CO2 emissions offset ~12% of national wetland carbon sinks.

Conclusions:

• China's lakes show an increasing trend in CO2 emissions, significantly impacting the terrestrial carbon budget.
• Lake expansion is a key factor driving these emission changes.
• Sustained monitoring is crucial for refining carbon budgets and informing climate mitigation policies.